Suspension rod assembly for automatic washer

ABSTRACT

A tube suspension system in a laundry appliance includes individual suspension assemblies each including a pair of hanger rods interconnected in axially adjustable assembly and preloaded in a direction opposite to the suspension loading by a coiled compression spring. The hanger rods are coupled and guided for parallel movement by an elongated, substantially cylindrical unit.

United States Patent [1 1 Weir et al.

[ 11 3,744,746 1 July 10, 1973 SUSPENSION ROD ASSEMBLY FOR AUTOMATIC WASHER [7 5] Inventors: Robert M. Weir, Benton Harbor;

Gerald K. Farrington, Saint Joseph, both of Mich.

[73] Assignee: Whirlpool Corporation, Benton Harbor, Mich.

[221 Filed: Sept. 23, 1971 [21] Appl. No.: 183,082

[52] US. Cl 248/18, 68/233, 210/364, 248/358 AA [51] Int. Cl Fl6t 15/00 [58] Field of Search 248/18, 54 R, 358 AA; 68/233, 23.1; 267/70; 210/364 [56] References Cited UNITED STATES PATENTS 3,268,082 8/1966 Galin 210/364 2,484 3/1842 Bacon 248/358 AA X 3,632,070 2/ 1970 Thayer 248/74 PB 3,102,706 9/1963 Goldsmith 248/54 R 3,321,940 5/1967 Brucken 248/18 X 3,306,082 2/ 1967 Hasegawa et a1. 68/233 X FOREIGN PATENTS OR APPLICATIONS 2,062,596 6/1971 Germany 85/85 453,846 1/1949 Canada 248/54 R Primary Examiner.l. Franklin Foss Attorney-Hill, Sherman, Meroni, (iross & Simpson [57] ABSTRACT A tube suspension system in a laundry appliance includes individual suspension assemblies each including a pair of hanger rods interconnected in axially adjustable assembly and preloaded in a direction opposite to the suspension loading by a coiled compression spring. The hanger rods are coupled and guided for parallel movement by an elongated, substantially cylindrical unit.

10 Claims, 4 Drawing Figures Pmmriuw 3.744.746

'INVENTORS K 550 M IV/k 2 4 5 F5 .4 eeuo A irms er SUSPENSION ROD ASSEMBLY FOR AUTOMATIC WASHER BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to laundry appliances, such as automatic washing, rinsing and drying machines, and more particularly refers to a suspension assembly for hanging a tub of the machine from a support cabinet in a manner to isolate the cabinet from vibrations caused by the motion of the basket with an unbalanced load.

2. Description of the Prior Art The elimination of excessive vibrations in automatic washing, rinsing and drying machines for home use has been an area of continuing development. Excessive vibrations usually occur when there is a non-uniform distribution of clothes in the rotating clothes container or basket as the same spins rapidly to centrifuge excess water from the clothes. While a high rate of spin is desirable during the centrifuging operation, the maximum rate of spin is limited by the capabilities of the tub suspension system to isolate the machine cabinet from the vibrations or oscillatory motion caused by the unbalanced load. A complex suspension system may permit a high rate of spin, however, in order to maintain the cost of the laundry appliance within the reach of most consumers, the suspension system should also be compact, inexpensive and easily assembled.

SUMMARY OF THE INVENTION A tub suspension system of the present invention includes a compact, easily assembled and reliable springmass-dampener system for suspending a floating base, on which a rotatable basket or clothes container of a clothes washing machine is mounted, from a support or cabinet in a manner to prevent vibration transfer to the cabinet during a normal operation of the machine and particularly as the basket is rapidly rotated during an extracting or centrifuging operation.

The suspension system has a plurality of angularly spaced apart suspension assemblies interconnecting the tub floating base to the cabinet. Each of the assemblies comprises first and second, parallel hanger arm parts or rods with one end of each rod being operatively anchored to the floating base or the support, respectively. A coiled compression spring surrounding the hanger rods interconnects the rods in axially adjustable assembly and preloads the rods in a direction opposite to the suspension loading, thereby to yieldably support the tub in the cabinet. Relative sliding movement of the rods in axial directions is retarded or dampened by friction bushings fitted over the rods near the anchored ends of the rods, thereby to complete the spring-massdampener system.

In order to facilitate assembly and provide a reliable, compact and inexpensive unit, the spring, the hanger rods and the friction bushings are retained in proper assembled relationship and operatively connected to the support and the floating base by a pair of integral, onepiece housings 'or coupling parts disposed respectively adjacent the support and the floating base. Each of the housings comprise a molding having first and second symmetrical parts hingedly joined together and together with one another forming an elongated, substantially cylindrical unit. The unit has an enclosure portion at oneend with a chamber for encasing and capturing the friction bushing, a pilot portion at an opposite end for entering the coils of the compression spring and an intermediate collar portion having means to receive and interconnect the linking end of one of the hanger rods therein and forming a radial shoulder on which an end of the spring is seated. The linking end of each of the rods is guided for parallel, axial movement relative to the opposite hanger rod by the opposite rod passing through the housing unit.

The first and second symmetrical parts of the housing are hingedly interconnected by a hinge web formed on the intermediate collar portion, thereby to facilitate the assembly of the housing around the friction bushing and around a head plate eccentrically mounted on the secured or connected ends of the hanger rod. Once the housing has been assembled around the friction bushing and the linking end of the hanger rod, a spring clip or retainer may be secured around the friction bushing, thereby providing a control over the frictional damping applied to the rod.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of an automatic laundry machine including a tub suspension system constructed in accordance with the principles of the present invention, with parts of the cabinet and tub broken away and with certain other parts shown in vertical section;

FIG. 2 is an enlarged, fragmentary view, partially in section, of one of the suspension rod assemblies of the suspension system of the present invention;

FIG. 3 is a plan view of an integral, one-piece housing utilized in the suspension rod assembly of FIG. 2 and illustrates the part in its molded form; and

FIG. 4 is an end view of the housing molding shown in FIG. 3 and illustrating the housing in its assembled configuration.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring to the drawing, an automatic washing, rinsing and extracting or centrifuging machine 10 includes a cabinet or shell 11 forming an enclosure and support for a tub 12. A clothes basket 13 having an apertured wall portion is rotatably mounted within the tub and adapted to receive clothes or other laundry material. Centrally disposed within the tub is an appropriate agitator 14 carried for rotary and oscillatory motion on a shaft 16 extending upwardly from a suitable transmission 17. While a perforated rotatable clothes basket is shown, it should be understood that the principles of the suspension system herein disclosed are applicable to so-called over-flow rinse types of machines wherein the clothes container forms its own tub.

The tub 12 is carried on a floating base 18 from which the transmission 17 and a motor 19 are suspended. A plurality of suspension links or assemblies 20, together forming a suspension system, suspend the floating base 18 from a mounting flange 21 attached to the supporting cabinet 11.

During operation of the automatic laundry appliance or washing machine 10, the tub 12 is first filled with soapy water or other laundry solution and the agitator 14 is oscillated via the transmission unit 17 and the motor 19. After completion of that operation, the water is drained from the tub l2 and the basket 13 is thereafter rotated at a high speed to extract or centrifuge the water from the clothes contained in the basket.

In the event the clothes are non-uniformly located or distributed within the basket during the extraction operation, the basket, tub, and base will together execute an oscillatory motion, which, if transmitted to the cabinet, may cause an undesirable and excessive vibration. The suspension system of the present invention, includ ing the suspension links or assemblies is designed to isolate the rotating and oscillating parts from the cabinet 11, thereby preventing vibration transfer.

In accordance with the present invention, and as best illustrated in FIG. 2, each of the suspension assemblies 20 comprise first and second, similar hanger arm parts or rods 22 and 23, with each rod having an anchored end 26 and a linking end portion 24. The anchored end portions 26 of the hanger rods 22 and 23 are operatively connected to the mounting flange 21 and the floating base 18, respectively, for movement therewith. An offset link or head plate 27 secured by welding or other suitable means to the linking end portion 24 and eccentrically mounted thereon has an aperture 28 slidably receiving the opposite one of the hanger rods 22 or 23 near its anchored end.

Each of the anchored end portions of the hanger rods 22 and 23 is received in a cushioning pad 29 having a hemispherical surface 31 in bearing engagement with a complemental hemispherical surface 32 formed in sockets respectively attached to the mounting flange 21 and the floating base 18. The hemispherical sockets are formed by cup-shaped members 33 attached to the associated one of the mounting flange and the floating base and configured to receive and capture the cushioning pads 29. Slidable movement of the anchored rod end portions 26 inwardly of the pads 29 is limited by jam nuts or similar fasteners as at 34.

A suitable, coiled compression spring 36 encircling an intermediate portion of the hanger rods 22 and 23 maintains the rods in an axially movable disposition and preloads the rods in a direction opposite to the suspension loading of the floating base 18 in a manner to yieldably support the floating base and the parts carried thereby from the mounting flange 21.

Relative axial movement of the rods is retarded or dampened by a pair of friction bushings 37 which surround the rod near the anchored end portions 26. In that manner, the suspension assembly including the hanger rods 22 and 23, the coiled compression spring 36 and the friction bushings 37, along with the mass of the parts carried on the floating base 18 provide a spring-mass-dampener system to attenuate the effect of the oscillatory motion due to an unbalanced load in the clothes basket 13 during the spinning or extracting operation. Each friction bushing 37 comprises a pair of molded, half-cylinder members 37a and 37b formed of a phenolic resin material impregnated with asbestos fibers. The half cylinders 37a and 37b are dimensioned such that they provide a longitudinal gap 38 when positioned on the rods 22 and 23, and include circumferential shoulder portions 37c and 37d.

In accordance with the principles of the present invention, the hanger rods 22 and 23, the friction bushing 37 and the compression spring 36 are maintained in proper assembled relationship, with the rods being guided for axial movement parallel to an axis of the coils of the compression spring, by a pair of identical, coupling members or housing parts 40, 40 respectively disposed about the head plates 27. Each of the housings 40 is an integral, one-piece molded part formed of a suitable material, such as polypropylene, and is characterized as comprising first and second symmetrical parts 40a and 40b hingedly joined together and acting together to form an elongated substantially cylindrical unit. The housing unit includes an enclosure portion 41 at one end for encasing the friction bushing 37, a pilot portion 42 at the opposite end sized and configured to enter the coils of the spring 36 and an intermediate collar portion 43 forming a radial shoulder 44 on which the opposite ends of the spring are seated.

The enclosure portion 41, which has a chamber formed by a cavity in each of the parts 40a and 40b, has a circumferentially slotted cylindrical wall 46 formed with an inner cylindrical surface 47 of the chamber which surface 47 is sized to closely fit around an outer, cylindrical surface 48 on the friction bushing 37. A radially inwardly extending flange 49 axially outwardly overlies an outer end of the friction bushing 37, thereby to axially retain and capture the bushing. The flange 49, which forms an end surface for the chamber forms an aperture 51 slidably receiving the unconnected end portion 26 of the associated rod 22 or 23.

The pilot portion 42 enters the coils of the compression spring 36 and is characterized by an outer, discontinuous, cylindrical surface 52 sized to closely confront an inner surface of the coils of the spring. In order to maintain the hanger rods 22 and 23 in a proper spaced apart relationship, the pilot portion has a pair of axially extended, radial recesses 53 and 54 separated by a central ridge 56 interposed between the rods. Each of the recesses 53 and 54, which are disposed on diametrically opposite sides of the pilot portion 42, has an arcuate bottom wall 57 formed with a radius of curvature complemental to that of the rods 22 and 23 and a pair of parallel sidewalls 58, 58 terminating at the surface 52. With the pilot portion 42 inserted into the spring 36, the rods 22 and 23 are maintained in a spaced apart relationship by the central ridge 56 and guided in the recesses 53 and 54 for relative axial movement parallel to an axis of the coils of the spring.

It is contemplated by the present invention to form the intermediate collar portion of the housing members 40 with an interior circular cavity 61 sized and configured to form means to encase and capture the associated head plate 27. In that manner, the housing 40 is secured to the adjoining one of the linking end portions 24 of the rods 22 and 23 for movement therewith. A blind aperture 62 in axial alignment with the recess 54 accepts the linking rod end portion 24 and has an undercut groove 63 providing clearance for excess weld material around a perimeter of the rod.

Diametrically opposite the blind aperture 62, a through bore 64 is formed in the intermediate collar portion 43 and disposed in axial alignment with an axis of the cylindrical wall 46 of the enclosure portion 41 and the recess 53. The through bore 64 is sized to slidably receive the adjoining anchored rod end portion 26, thereby to enable relative sliding movement between the free or unconnected rod end portion and the housing 40.

The housing 40 is molded in its opened configuration, as illustrated in FIG. 3, with a flexible hinge web 71 interconnecting the symmetrical parts or halves 40a and 40b at the intermediate collar portions 43. In order to facilitate assembly of the housing 41 around the friction bushing 37 and the rods 22 and 23, the split line of the molded part is on a radial plane containing the axes of the cylindrical wall 46 of the enclosure portion, the through bore 64 in the intermediate collar portion and each of the arcuate bottom wall portions 57 of the recesses 53 and 54. Thus, the symmetrical parts have confronting face surfaces 40c and 40d lying on the radial plane containing the split line and bisecting the recesses 53 and 54.

The suspension links or assemblies are assembled by passing the hanger rods 22 and 23 through the coils of the compression spring 36 with the anchored end portions 26 received in the clearance apertures 28 of the head plates 27, and then the friction bushings 37 are fitted over the anchored ends. Subsequent to that assembly, the housings 40 are closed around the friction bushings 37, the head plates 27 and the rods 22 and 23, and then the rods are axially moved until the pilot portion 42 enters the coils of the compression spring, which subsequently holds the housing in its assembled, closed configuration. The location of the split line dividing the housing into the symmetrical parts 40a and 40b is positioned to facilitate assembly by enabling the housing to be closed or wrapped around the rods.

A retainer clip or band 65 encircles shoulder portions 37c and 37d of friction bushing 37. The shoulder portions 37c and 37d extend through circumferential slots 74a and 74b in the cylindrical housing wall 46. The clip 65 may have any suitable configuration which will apply a normal force to bushing sections 37a and 37b. Inasmuch as the normal force applied to bushing sections 37a and 37b determines the frictional force and hence the degree of damping action provided to the rods 22 and 23, the clip 65 provides a convenient means for controlling and adjusting the damping action of the suspension assembly 20.

As will be appreciated by those skilled in the art, the suspension assembly provided herein has numerous advantages when used with centrifuging machines such as automatic washers. The damping action of the individual suspension assemblies can easily be adjusted to suit the requirements of a particular application. If desired, the damping action can be varied once the suspension assembly is installed merely by changing the force applied to the damping material by the clip 65. Further, replacement of the damping material can be easily and quickly accomplished.

The embodiments of the invention in which the exclusive property or privilege is claimed are defined as follows:

1. Tub suspension means for use in a laundry appliance of the type having a cabinet and a floating base comprising:

first and second suspension rods disposed in parallel relationship;

biasing means comprising a coil compression spring encircling said first and second suspension rods, said spring interconnecting said rods in axially movable assembly and preloading said rods in one direction;

dampening means comprising a pair of friction bush ings respectively disposed in frictional sliding engagement with each of said rods in proximity to one end of each rod;

a pair of anchoring means operatively anchoring said one end of one rod to the cabinet and said one end of the other rod to the adjoining floating base, respectively; and

a pair of linking means operatively linking another end of each of said rods to the opposite one of said rods, said linking means having slidably receiving means for the opposite one of said rods, each of said linking means comprising a one-piece unit having first and second symmetrical parts hingedly joined together, said parts being movable together in an assembled relationship to form an elongated unit, said unit comprising: an enclosure portion at one end of said unit, said enclosure portion having a cavity in each of said first and second symmetrical parts, said cavities coacting when said parts are in the assembled relationship to form a chamber for enclosing and capturing an associated one of said friction bushmgs;

a pilot portion at the opposite end of said unit for entering the coils of said spring; and

an intermediate collar portion forming a radial shoulder on which an end of the coils of said spring are seated, with said other end of the associated one of said rods being interconnected in said intermediate portion for movement with said coupling means. 2. A housing for use with a tub suspension, comprismg:

first and second symmetrical parts hingedly joined together and being movable together in an assembled relationship to form an elongated, substantially cylindrical unit, said unit comprising: an enclosure portion at one end of said unit, said enclosure portion having a cavity in each of said first and second symmetrical parts, said cavities coacting when said parts are in the assembled relationship to form a chamber for enclosing and capturing a friction bushing fitted about a first hanger rod passing therethrough,

a pilot portion at the opposite end for entering the coils of a compression spring, and

an intermediate collar portion having a hinge interconnecting said first and second parts and forming a radial shoulder on which an end of the coils of the spring is seated, said collar portion having means to receive and interconnect an end of a second hanger rod for movement with said unit.

3. A housing as defined in claim 2 and further characterized by said unit being composed of a plastic material with said hinge being formed integrally with said first and second symmetrical parts.

4. A housing as defined in claim 2 and further characterized by a retaining clip encircling said enclosure portion and maintaining said first and second parts in the assembled relationship.

5. A housing as defined in claim 2 and further characterized by:

said pilot portion having outer parti-cylindrical surface portions sized to be closely received within the coil of the spring, and

means forming a pair of diametrically, oppositely disposed, axially elongated, radial recesses in said pilot portion for receiving respective ones of said first and second hanger rods,

whereby said hanger rods are guided for axial movement parallel to an axis of the coils of the spring.

6. A housing as defined in claim 5, wherein the friction bushing includes a cylindrical member, and further characterized by:

said chamber of said enclosure portion having an interior cylindrical wall surface sized to closely fit over an outer surface of said cyli'fidrical friction bushing.

7. A housing as defined in claim 6 and further characterized by said collar portion having a through bore formed therein in axial alignment with said cylindrical surface of said chamber and in alignment with one of said recesses for slidably receiving said first hanger rod.

8. A housing as defined in claim 7 and further characterized by said first and second symmetrical parts having confronting, face surfaces lying on a plane containing the axes of said cylindrical surface of said chamber and bisecting said recess thereby to facilitate a wraparound assembly of the housing part over said rods and said friction bushing.

9. A housing as defined in claim 2, wherein said second hanger rod has a head plate secured thereto and apertured to slidably receive said first hanger rod, and further characterized by said means of said intermediate collar portion having an interior cavity formed therein and sized to receive and enclose the head plate connected to said second hanger rod for interconnecting the same to said unit for movement therewith.

10. A housing for use with a tub suspension, utilizing a first hanger bar and a second hanger bar and a coil compression spring, comprising:

first and second symmetrical parts of, plastic material joined together by an integral hinge, said first and second parts being movable on said hinge from an opened to an assembled condition to form an elongated, substantially cylindrical unit, said unit comprising:

an enclosure portion at one end having an interior cylindrical wall surface sized to closely fit over an outer surface of a cylindrical friction bushing fitted about the first hanger bar passing through the portion and said portion having a radially inwardly extending flange at one end of the cylindrical wall surface to overlie an outer end of the frictional bushing to enclose and capture said bushing within said unit,

a pilot portion at the opposite end of the unit, said pilot portion having an outer parti-cylindrical surface portion sized to be closely received within the coil of the compression spring, said pilot portion having means forming a pair of diametrically, oppositely disposed axially elongated radial recesses in said pilot portion for receiving respective lengths of the first and second hanger bars so that the hanger bars are guided for axial movement parallel to an axis of the coil of the spring,

an intermediate collar portion between the pilot portion and enclosure portion, said collar portion having the integral hinge for interconnecting the first and second parts together and forming a radial shoulder on which the end of the coil of the spring is seated, said collar portion having an interior cavity formed therein of a size to receive and enclose a head plate connected to the second hanger bar for interconnecting the hanger bar to said unit for movement therewith, and

said housing including a retaining clip encircling said enclosure portion for maintaining said first and second parts in the assembled relationship. 

1. Tub suspension means for use in a laundry appliance of the type having a cabinet and a floating base comprising: first and second suspension rods disposed in parallel relationship; biasing means comprising a coil compression spring encircling said first and second suspension rods, said spring interconnecting said rods in axially movable assembly and preloading said rods in one direction; dampening means comprising a pair of friction bushings respectively disposed in frictional sliding engagement with each of said rods in proximity to one end of each rod; a pair of anchoring means operatively anchoring said one end of one rod to the cabinet and said one end of the other rod to the adjoining floating base, respectively; and a pair of linking means operatively linking another end of each of said rods to the opposite one of said rods, said linking means having slidably receiving means for the opposite one of said rods, each of said linking means comprising a one-piece unit having first and second symmetrical parts hingedly joined together, said parts being movable together in an assembled relationship to form an elongated unit, said unit comprising: an enclosure portion at one end of said unit, said enclosure portion having a cavity in each of said first and second symmetrical parts, said cavities coacting when said parts are in the assembled relationship to form a chamber for enclosing and capturing an associated one of said friction bushings; a pilot portion at the opposite end of said unit for entering the coils of said spring; and an intermediate collar portion forming a radial shoulder on which an end of the coils of said spring are seated, with said other end of the associated one of said rods being interconnected in said intermediate portion for movement with said coupling means.
 2. A housing for use with a tub suspension, comprising: first and second symmetrical parts hingedly joined together and being movable together in an assembled relationship to form an elongated, substantially cylindrical unit, said unit comprising: an enclosure portion at one end of said unit, said enclosure portion having a cavity in each of said first and second symmetrical parts, said cavities coacting when said parts are in the assembled relationship to form a chamber for enclosing and capturing a friction bushing fitted about a first hanger rod passing therethrough, a pilot portion at the opposite end for entering the coils of a compression spring, and an intermediate collar portion having a hinge interconnecting said first and second parts and forming a radial shoulder on which an end of the coils of the spring is seated, said collar portion having means to receive and interconnect an end of a second hanger rod for movement with said unit.
 3. A housing as defined in claim 2 and further characterized by said unit being composed of a plastic material with said hinge being formed integrally with said first and second symmetrical parts.
 4. A housing as defined in claim 2 and further characterized by a retaining clip encircling said enclosure portion and maintaining said first and second parts in the assembled relationship.
 5. A housing as defined in claim 2 and further characterized by: said pilot portion having outer parti-cylindrical surface portions sized to be closely received within the coil of the spring, and means forming a pair of diametrically, oppositely disposed, axially elongated, radial recesses in said pilot portion for receiving respective ones of said first and second hanger rods, whereby said hanger rods are guided for axial movement parallel to an axis of the coils of the spring.
 6. A housing as defined in claim 5, wherein the friction bushing includes a cylindrical member, and further characterized by: said chamber of said enclosure portion having an interior cylindrical wall surface sized to closely fit over an outer surface of said cylindrical friction bushing.
 7. A housing as defined in claim 6 and further characterized by said collar portion having a through bore formed therein in axial alignment with said cylindrical surface of said chamber and in alignment with one of said recesses for slidably receiving said first hanger rod.
 8. A housing as defined in claim 7 and further characterized by said first and second symmetrical parts having confronting, face surfaces lying on a plane containing the axes of said cylindrical surface of said chamber and bisecting said recess thereby to facilitate a wrap-around assembly of the housing part over said rods and said friction bushing.
 9. A housing as defined in claim 2, wherein said second hanger rod has a head plate secured thereto and apertured to slidably receive said first hanger rod, and further characterized by said means of said intermediate collar portion having an interior cavity formed therein and sized to receive and enclose the head plate connected to said second hanger rod for interconnecting the same to said unit for movement therewith.
 10. A housing for use with a tub suspension, utilizing a first hanger bar and a second hanger bar and a coil compression spring, comprising: first and second symmetrical parts of plastic material joined together by an integral hinge, said first and second parts being movable on said hinge from an opened to an assembled condition to form an elongated, substantially cylindrical unit, said unit comprising: an enclosure portion at one end having an interior cylindrical wall surface sized to closely fit over an outer surface of a cylindrical friction bushing fitted about the first hanger bar passing through the portion and said portion having a radially inwardly extending flange at one end of the cylindrical wall surface to overlie an outer end of the frictional bushing to enclose and capture said bushing within said unit, a pilot portion at the opposite end of the unit, said pilot portion having an outer parti-cylindrical surface portion sized to be closely received within the coil of the compression spring, said pilot portion having means forming a pair of diametrically, oppositely disposed axially elongated radial recesses in said pilot portion for receiving respective lengths of the first and second hanger bars so that the hanger bars are guided for axial movement parallel to an axis of the coil of the spring, an intermediate collar portion between the pilot portion and enclosure portion, said collar portion having the integral hinge for interconnecting the first and second parts together and forming a radial shoulder on which the end of the coil of the sprIng is seated, said collar portion having an interior cavity formed therein of a size to receive and enclose a head plate connected to the second hanger bar for interconnecting the hanger bar to said unit for movement therewith, and said housing including a retaining clip encircling said enclosure portion for maintaining said first and second parts in the assembled relationship. 